Just when you thought the Calgary Stampeders had turned the corner, they get schooled.

Old schooled.

Blindsided late by a veteran group of Toronto Argos who know the virtues of focusing on all the little things needed to win, the Stampeders once again find themselves reeling from, well, their own mistakes.

Hanging tough most of the night in a defensive battle that saw the Stamps come within a few yards of winning on a last-minute Sandro DeAngelis field goal, Calgary spent the second half exhibiting the type of mental lapses that have plagued the club for five years.

Ruining the latest in a string of stellar efforts from quarterback Henry Burris, the Stamps allowed Argos return specialist Bashir Levingston to run back a punt and a missed field goal for 100-yard-plus touchdowns in the final few minutes of a 25-16 loss, ending any hopes of winning back-to-back games for the first time since 2002.

Looking back on the club's fifth loss in nine outings, the Stamps can look at several brain freezes contributing to the sickening collapse:

* A fake punt snapped to Brian Clark in the third quarter ended with a comical stumbling act that turned the ball over and resulted in an Argos punt single that loomed large in the final minute of the game.

* A brilliant fourth-quarter interception by Stamps defensive back Trey Young was nullified seconds later as he turned upfield only to get smoked by one of the biggest hits of the year by Robert Baker. Young fumbled and the Argos recovered the ball, kicked a field goal and ended any momentum the Stamps were generating.

* After Burris responded brilliantly by answering to a 109-yard Levingston punt return with a late TD to make it 18-16 for the Argos, coach Tom Higgins elected to go for a single-point convert instead of trying to tie the game with two minutes left. An Argos offside allowed him to change his mind and save him from heaps of criticism. Yet, Burris' lunge fell inches short, necessitating the Stamps' final drive.

* Burris led the Stamps on the last-minute drive, which was marred by a Nik Lewis dropped ball that would have allowed DeAngelis to attempt a more reasonable field goal attempt than the 54-yarder he fell just short of.

* After the missed field goal, the Stamps failed to attack or pin Levingston in the endzone, allowing him to make a mockery of the Stamps for the second time, leading to a 111-yard touchdown run.

In short, the special-teams players return home looking rather silly, while several others need to realize momentary lapses like the ones exhibited by Lewis, Young, Higgins and DeAngelis are the difference between winners and losers. While he can't be grilled for missing the last-minute field goal, DeAngelis can be criticized for missing a much easier field goal at the end of the first half.

On the verge of being rewarded for a building process that began in January, the Stamps squandered a chance to establish momentum, not to mention any credibility as a West contender.

Instead, they'll return home with 12 days to think about and improve on an effort that looked so solid most of the night on both sides of the ball. Joffrey Reynolds ran well, Burris made smart decisions and great passes all night and the defence held tight.

But when it mattered most, the Stamps imploded, allowing 17 fourth-quarter points.

If nothing else, the loss should reinforce the importance of focus at all times.

Otherwise, it'll be quite some time before the Stamps return to respectability.